Wednesday, July 3, 2013

Camera Calibration Needed!

I added the lens correction equations described here to our MATLAB code last night:

If we can figure out the "a", "b", and "c" parameters that Hugin uses (by calibrating cameras, which sounds easier than it seems to be), then we can figure out if this helps with the further away control points that weren't coming out quite right yesterday. 

Without using multiple pictures or lens distortion correction, here's where we are at.  (This is in our google drive document as well.)  I think that we should be able to do better in the lab (these numbers might be fine for the real stream).

For square 3 in red-DSCN0094:
Error to Square (These seem nice)
Length           0.85%
Diagonal 1     0.52%
Diagonal 2     0.33%

Error lengths between control points
DE   22.8%
EF   7.3%
EI   10.8%
EJ   8.2%
FH  1.4%
FI   2.2%
FJ   7.4%
HI   2.2%
HJ   7.5%
IJ   11%


  1. This might also be useful -- not sure.

  2. Hmm... I found a better set of tutorials, suggested by the maintainers of the lensfun database, so I think it's probably better.

    In particular, the first tutorial on that page includes a video tutorial:

    This video tutorial says that you need to take a picture of something with straight lines *at least 8 meters away* (in the HTML doc, it says 1 meter may be enough, but our photos of the paper are definitely too close), since distortion can be weird at close range. Did you try with the meter sticks? It might work better...